1. Field of the Invention
The present invention relates to an inorganic composite substrate of high rigidity which is suitable for many applications such as electronic and structural materials.
2. Description of the Prior Art
As substrates for electronic components, such as IC substrates or magnetic head substrates, or as structural materials in various industrial areas, various substrates fabricated from materials possessing properties appropriate to their particular applications are employed. For example, materials such as resin-ceramic and metal-ceramic composites are well known as substrates for electronic circuits. However, substrates fabricated from the aforementioned resin-ceramic composites have the shortcoming of low rigidity. The metal-ceramic composites have, for example, the form of metal particles dispersed in a ceramic base layer. This metal-ceramic composite is relatively rigid. However, in substrates composed of such a composite, the amount of the ceramic material compared with that of metal particles is large, thus, the properties of metal could hardly be obtained. Moreover, the distances between the particles dispersed in the ceramic layer is large, and consequently the mechanical strength of such substrates is low.
Materials such as titanium-magnesium-nickel oxide composites are widely used as magnetic head substrates. However, the degree of wear incurred during use is different for titanium oxide, magnesium oxide and nickel oxide, and consequently minute irregularities appear on the surface of the substrate. Moreover, unduly low electrical resistivity constitutes another shortcoming of this type of composite material. Materials for use as magnetic head substrates should desirably possess good wear resistance, and proper compatibility (such as compatibility of expansion coefficient) with the alloys from which magnetic heads are composed.
At present, high thermal conductivity is considered as a desirable property in IC substrates mainly made of aluminum, while heat resistance, good electrical insulation characteristics and high thermal conductivity are desirable in IC substrates mainly made of a resin.
For example, materials for magnetic head substrates and IC substrates should desirably possess the special properties combining good workability and high mechanical strength with good electrical insulation characteristics.